#include "./md5.h"
#include <string.h>

namespace utils::md5 {

#define F(x, y, z) ((x & y) | (~x & z))
#define G(x, y, z) ((x & z) | (y & ~z))
#define H(x, y, z) (x ^ y ^ z)
#define I(x, y, z) (y ^ (x | ~z))
#define ROTATE_LEFT(x, n) ((x << n) | (x >> (32 - n)))
#define FF(a, b, c, d, x, s, ac)                                               \
    {                                                                          \
        a += F(b, c, d) + x + ac;                                              \
        a = ROTATE_LEFT(a, s);                                                 \
        a += b;                                                                \
    }
#define GG(a, b, c, d, x, s, ac)                                               \
    {                                                                          \
        a += G(b, c, d) + x + ac;                                              \
        a = ROTATE_LEFT(a, s);                                                 \
        a += b;                                                                \
    }
#define HH(a, b, c, d, x, s, ac)                                               \
    {                                                                          \
        a += H(b, c, d) + x + ac;                                              \
        a = ROTATE_LEFT(a, s);                                                 \
        a += b;                                                                \
    }
#define II(a, b, c, d, x, s, ac)                                               \
    {                                                                          \
        a += I(b, c, d) + x + ac;                                              \
        a = ROTATE_LEFT(a, s);                                                 \
        a += b;                                                                \
    }

using namespace std;

static const uint8_t PADDING[] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0,    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

static uint32_t count[2];
static uint32_t state[4];
static uint8_t buffer[64];
static uint32_t x[64];
static uint8_t bits[8];

static void md5_transform(uint32_t state[4], const uint8_t block[64],
                          uint32_t *x);
static void md5_decode(uint32_t *output, const uint8_t *input, uint32_t len);
static void md5_encode(uint8_t *output, const uint32_t *input, uint32_t len);

void md5_init();
void md5_final(uint8_t digest[16]);
void md5_update(const void *input, uint32_t size);

void sum(const void *data, uint32_t size, uint8_t digest[16]) {
    md5_init();
    md5_update(data, size);
    md5_final(digest);
}

void md5_init() {
    count[0] = 0;
    count[1] = 0;
    state[0] = 0x67452301;
    state[1] = 0xEFCDAB89;
    state[2] = 0x98BADCFE;
    state[3] = 0x10325476;
}

void md5_final(uint8_t digest[16]) {
    uint32_t index = 0, padlen = 0;
    index = (count[0] >> 3) & 0x3F;
    padlen = (index < 56) ? (56 - index) : (120 - index);
    md5_encode(bits, count, 8);
    md5_update(PADDING, padlen);
    md5_update(bits, 8);
    md5_encode(digest, state, 16);
}

void md5_update(const void *input, uint32_t size) {
    uint32_t i = 0, index = 0, partlen = 0;
    auto in = static_cast<const uint8_t *>(input);
    index = (count[0] >> 3) & 0x3F;
    partlen = 64 - index;
    count[0] += size << 3;
    if (count[0] < (size << 3)) {
        count[1]++;
    }
    count[1] += size >> 29;

    if (size >= partlen) {
        memcpy(&buffer[index], input, partlen);
        md5_transform(state, buffer, x);
        for (i = partlen; i + 64 <= size; i += 64) {
            md5_transform(state, in + i, x);
        }
        index = 0;
    } else {
        i = 0;
    }
    memcpy(&buffer[index], &in[i], size - i);
}

static void md5_encode(uint8_t *output, const uint32_t *input, uint32_t len) {
    uint32_t i = 0, j = 0;
    while (j < len) {
        output[j] = input[i] & 0xFF;
        output[j + 1] = (input[i] >> 8) & 0xFF;
        output[j + 2] = (input[i] >> 16) & 0xFF;
        output[j + 3] = (input[i] >> 24) & 0xFF;
        i++;
        j += 4;
    }
}

static void md5_decode(uint32_t *output, const uint8_t *input, uint32_t len) {
    uint32_t i = 0, j = 0;
    while (j < len) {
        output[i] = (input[j]) | (input[j + 1] << 8) | (input[j + 2] << 16) |
                    (input[j + 3] << 24);
        i++;
        j += 4;
    }
}

static void md5_transform(uint32_t state[4], const uint8_t block[64],
                          uint32_t *x) {
    uint32_t a = state[0];
    uint32_t b = state[1];
    uint32_t c = state[2];
    uint32_t d = state[3];

    md5_decode(x, block, 64);

    FF(a, b, c, d, x[0], 7, 0xd76aa478);   /* 1 */
    FF(d, a, b, c, x[1], 12, 0xe8c7b756);  /* 2 */
    FF(c, d, a, b, x[2], 17, 0x242070db);  /* 3 */
    FF(b, c, d, a, x[3], 22, 0xc1bdceee);  /* 4 */
    FF(a, b, c, d, x[4], 7, 0xf57c0faf);   /* 5 */
    FF(d, a, b, c, x[5], 12, 0x4787c62a);  /* 6 */
    FF(c, d, a, b, x[6], 17, 0xa8304613);  /* 7 */
    FF(b, c, d, a, x[7], 22, 0xfd469501);  /* 8 */
    FF(a, b, c, d, x[8], 7, 0x698098d8);   /* 9 */
    FF(d, a, b, c, x[9], 12, 0x8b44f7af);  /* 10 */
    FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], 7, 0x6b901122);  /* 13 */
    FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[1], 5, 0xf61e2562);   /* 17 */
    GG(d, a, b, c, x[6], 9, 0xc040b340);   /* 18 */
    GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);  /* 20 */
    GG(a, b, c, d, x[5], 5, 0xd62f105d);   /* 21 */
    GG(d, a, b, c, x[10], 9, 0x2441453);   /* 22 */
    GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);  /* 24 */
    GG(a, b, c, d, x[9], 5, 0x21e1cde6);   /* 25 */
    GG(d, a, b, c, x[14], 9, 0xc33707d6);  /* 26 */
    GG(c, d, a, b, x[3], 14, 0xf4d50d87);  /* 27 */
    GG(b, c, d, a, x[8], 20, 0x455a14ed);  /* 28 */
    GG(a, b, c, d, x[13], 5, 0xa9e3e905);  /* 29 */
    GG(d, a, b, c, x[2], 9, 0xfcefa3f8);   /* 30 */
    GG(c, d, a, b, x[7], 14, 0x676f02d9);  /* 31 */
    GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[5], 4, 0xfffa3942);   /* 33 */
    HH(d, a, b, c, x[8], 11, 0x8771f681);  /* 34 */
    HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[1], 4, 0xa4beea44);   /* 37 */
    HH(d, a, b, c, x[4], 11, 0x4bdecfa9);  /* 38 */
    HH(c, d, a, b, x[7], 16, 0xf6bb4b60);  /* 39 */
    HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], 4, 0x289b7ec6);  /* 41 */
    HH(d, a, b, c, x[0], 11, 0xeaa127fa);  /* 42 */
    HH(c, d, a, b, x[3], 16, 0xd4ef3085);  /* 43 */
    HH(b, c, d, a, x[6], 23, 0x4881d05);   /* 44 */
    HH(a, b, c, d, x[9], 4, 0xd9d4d039);   /* 45 */
    HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[2], 23, 0xc4ac5665);  /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[0], 6, 0xf4292244);   /* 49 */
    II(d, a, b, c, x[7], 10, 0x432aff97);  /* 50 */
    II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[5], 21, 0xfc93a039);  /* 52 */
    II(a, b, c, d, x[12], 6, 0x655b59c3);  /* 53 */
    II(d, a, b, c, x[3], 10, 0x8f0ccc92);  /* 54 */
    II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[1], 21, 0x85845dd1);  /* 56 */
    II(a, b, c, d, x[8], 6, 0x6fa87e4f);   /* 57 */
    II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[6], 15, 0xa3014314);  /* 59 */
    II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[4], 6, 0xf7537e82);   /* 61 */
    II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[2], 15, 0x2ad7d2bb);  /* 63 */
    II(b, c, d, a, x[9], 21, 0xeb86d391);  /* 64 */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

} // namespace utils::md5
